Tolerance To Water Deficit Stress Research Articles

Aeluropus littoralis stress-associated protein promotes water deficit resilience in engineered durum wheat

Global climate change-related water deficit negatively affect the growth, development and yield performance of multiple cereal crops, including durum wheat. Therefore, the improvement of water-deficit stress tolerance in durum wheat varieties in arid and semiarid areas has become imperative for food security. Herein, we evaluated the water deficiency resilience potential of two marker-free transgenic durum wheat lines (AlSAP-lines: K9.3 and K21.3) under well-watered and water-deficit stress conditions at both physiological and agronomic levels. These two lines overexpressed the AlSAP gene, isolated from the halophyte grass Aeluropus littoralis, encoding a stress-associated zinc finger protein containing the A20/AN1 domains. Under well-watered conditions, the wild-type (WT) and both AlSAP-lines displayed comparable performance concerning all the evaluated parameters. Ectopic transgene expression exerted no adverse effects on growth and yield performance of the durum wheat plants. Under water-deficit conditions, no significant differences in the plant height, leaf number, spike length, and spikelet number were observed between AlSAP-lines and WT plants. However, compared to WT, the AlSAP-lines exhibited greater dry matter production, greater flag leaf area, improved net photosynthetic rate, stomatal conductance, and water use efficiency. Notably, the AlSAP-lines displayed 25 % higher grain yield (GY) than the WT plants under water-deficit conditions. The RT-qPCR-based selected stress-related gene (TdDREB1, TdLEA, TdAPX1, and TdBlt101-2) expression analyses indicated stress-related genes enhancement in AlSAP-durum wheat plants under both well-watered and water-deficit conditions, potentially related to the water-deficit resilience. Collectively, our findings support that the ectopic AlSAP expression in durum wheat lines enhances water-deficit resilience ability, thereby potentially compensate for the GY loss in arid and semi-arid regions.

High-throughput chlorophyll fluorescence image-based phenotyping for water deficit stress tolerance in wheat

High-throughput chlorophyll fluorescence image-based phenotyping for water deficit stress tolerance in wheat

Heterotic Analysis (Oryza sativa L.) in Drought Tolerant Rice Accessions

Water-deficit stress tolerance in rice is important for maintaining stable yield, especially under rain-fed ecosystem. After a thorough drought-tolerance screening of 200 rice genotypes from DBT, Network Rice Project in our previous study, 19 rice lines were selected for drought tolerance capacity. Six randomly chosen rice accessions out of these 19 rice accessions were further used for creation of F1 Hybrids for heterosis study. The study investigates the heterosis effects on key agronomic traits in rice hybrids, including days to 50% flowering, plant height, number of effective tillers per plant, spikelet fertility, grain yield per plant, and 100-grain weight. Analysis reveals diverse heterotic effects across hybrid combinations, with some hybrids exhibiting significant negative heterosis for traits like days to flowering and plant height, indicating potential for early maturation and dwarfism, respectively. Conversely, positive heterosis is observed in traits such as number of effective tillers, spikelet fertility, grain yield, and 100-grain weight, highlighting the potential for enhanced productivity. Notably, certain hybrids consistently display strong positive heterosis across multiple traits, suggesting their suitability for breeding programs aimed at improving overall yield and agronomic performance.

Overexpression of soybean GmNAC19 and GmGRAB1 enhances root growth and water-deficit stress tolerance in soybean.

Soybean (Glycine max) is an important crop in agricultural production where water shortage limits yields in soybean. Root system plays important roles in water-limited environments, but the underlying mechanisms are largely unknown. In our previous study, we produced a RNA-seq dataset generated from roots of soybean at three different growth stages (20-, 30-, and 44-day-old plants). In the present study, we performed a transcriptome analysis of the RNA-seq data to select candidate genes with probable association with root growth and development. Candidate genes were functionally examined in soybean by overexpression of individual genes using intact soybean composite plants with transgenic hairy roots. Root growth and biomass in the transgenic composite plants were significantly increased by overexpression of the GmNAC19 and GmGRAB1 transcriptional factors, showing up to 1.8-fold increase in root length and/or 1.7-fold increase in root fresh/dry weight. Furthermore, greenhouse-grown transgenic composite plants had significantly higher seed yield by about 2-fold than control plants. Expression profiling in different developmental stages and tissues showed that GmNAC19 and GmGRAB1 were most highly expressed in roots, displaying a distinct root-preferential expression. Moreover, we found that under water-deficit conditions, overexpression of GmNAC19 enhanced water stress tolerance in transgenic composite plants. Taken together, these results provide further insights into the agricultural potential of these genes for development of soybean cultivars with improved root growth and enhanced tolerance to water-deficit conditions.

Improvement of water deficit stress tolerance of Impatiens walleriana shoots grown in vitro by methyl jasmonate

Improvement of water deficit stress tolerance of Impatiens walleriana shoots grown in vitro by methyl jasmonate

Comparative Study of Trehalose and Trehalose 6-Phosphate to Improve Antioxidant Defense Mechanisms in Wheat and Mustard Seedlings under Salt and Water Deficit Stresses

Trehalose 6-phosphate (T6P) regulates sugar levels and starch metabolism in a plant cell and thus interacts with various signaling pathways, and after converting T6P into trehalose (Tre), it acts as a vital osmoprotectant under stress conditions. This study was conducted using wheat (Triticum aestivum L. cv. Norin 61) and mustard (Brassica juncea L. cv. BARI sharisha 13) seedlings to investigate the role of Tre and T6P in improving salt and water deficit stress tolerance. The seedlings were grown hydroponically using Hyponex solution and exposed to salt (300 and 200 mM NaCl for wheat and mustard, respectively) and water deficit (20 and 12% PEG 6000 for wheat and mustard, respectively) stresses with or without Tre and T6P. The study demonstrated that salt and water deficit stress negatively influenced plant growth by destroying photosynthetic pigments and increasing oxidative damage. In response to salt and water deficit stresses, the generation of H2O2 increased by 114 and 67%, respectively, in wheat seedlings, while in mustard, it increased by 86 and 50%, respectively. Antioxidant defense systems were also altered by salt and water deficit stresses due to higher oxidative damage. The AsA content was reduced by 65 and 38% in wheat and 61 and 45% in mustard under salt and water deficit stresses, respectively. The subsequent negative results of salinity and water deficit can be overcome by exogenous application of Tre and T6P; these agents reduced the oxidative stress by decreasing H2O2 and TBARS levels and increasing enzymatic and non-enzymatic antioxidants. Moreover, the application of Tre and T6P decreased the accumulation of Na in the shoots and roots of wheat and mustard seedlings. Therefore, the results suggest that the use of Tre and T6P is apromising strategy to alleviate osmotic and ionic toxicity in plants under salt and water deficit stresses.

Expression profiling of flavonoid biosynthesis genes in association with accumulation of flavonoid compounds in rice under water deficit stress

Aim: To investigate whether the phenolic and flavonoid contents have any direct relation with the water deficit stress tolerance in rice. If so, then, which genes in the flavonoid biosynthesis pathway are involved in the tolerance mechanism was explored by comparing a well-known water deficit tolerant cv. Nagina 22 (N22) as experiment material along with a sensitive cv. Pusa Sugandh 2 (PS2). Methodology: Water deficit stress was imposed on N22 (drought tolerant) and PS2 (drought sensitive) cultivars at the seedling stage by withholding water for 7days. Further, the expression level of flavonoid biosynthesis genes (OsCHS, OsCHI, OsF3H, OsF3’H, OsDFR, and OsANS) and the accumulation of total contents of phenolics and flavonoids in rice leaves of N22 and PS2 under water deficit stress were also investigated. Results: Quantitative RT-PCR analysis revealed enhanced expression of six major genes of the flavonoid biosynthesis pathway, namely OsCHS, OsCHI, OsF3H, OsF3’H, OsDFR, and OsANS in the drought tolerant cv. N22 compared to the drought sensitive cv. PS2 under water deficit stress. Accumulation of total phenolics and flavonoids compounds increased during water deficit stress in both the genotypes, but, it was significantly higher in N22 as compared to PS2. Interpretation: Our findings conclude that enhanced drought tolerance is positively correlated with an enhanced transcription of flavonoid biosynthesis genes and higher flavonoid content, suggesting that there could be differences in the genetic control of flavonoid metabolism in rice for drought stress response that, the enhanced expression and accumulation of flavonoids is promising strategy for rice improvement.

Methionine Promotes the Growth and Yield of Wheat under Water Deficit Conditions by Regulating the Antioxidant Enzymes, Reactive Oxygen Species, and Ions.

The individual application of pure and active compounds such as methionine may help to address water scarcity issues without compromising the yield of wheat. As organic plant growth stimulants, amino acids are popularly used to promote the productivity of crops. However, the influence of the exogenous application of methionine in wheat remains elusive. The present investigation was planned in order to understand the impact of methionine in wheat under drought stress. Two wheat genotypes were allowed to grow with 100% field capacity (FC) up to the three-leaf stage. Twenty-five-day-old seedlings of two wheat genotypes, Galaxy-13 and Johar-16, were subjected to 40% FC, denoted as water deficit-stress (D), along with 100% FC, called control (C), with and without L-methionine (Met; 4 mM) foliar treatment. Water deficit significantly reduced shoot length, shoot fresh and dry weights, seed yield, photosynthetic, gas exchange attributes except for transpiration rate (E), and shoot mineral ions (potassium, calcium, and phosphorus) in both genotypes. A significant increase was recorded in superoxide dismutase (SOD), catalase (CAT), hydrogen peroxide (H2O2), malondialdehyde (MDA), and sodium ions (Na+) due to water deficiency. However, foliar application of Met substantially improved the studied growth, photosynthetic, and gas exchange attributes with water deficit conditions in both genotypes. The activities of SOD, POD, and CAT were further enhanced under stress with Met application. Met improved potassium (K), calcium (Ca2+), and phosphorus (P) content. In a nutshell, the foliar application of Met effectively amended water deficit stress tolerance by reducing MDA and H2O2 content under water deficit conditions in wheat plants. Thus, we are able to deduce a positive association between Met-induced improved growth attributes and drought tolerance.

Evaluation of Cowpea Morpho-physiological and Yield Responses to Vegetative and Pre-Anthesis Water-Deficit Stress Tolerance under Greenhouse Conditions

Cowpea production is severely hindered by water scarcity; thus, understanding morpho-physiological response mechanisms of known drought-tolerant cultivars under water-deficit stress is critical to identify and establish representative yield-related traits of climate-hardy cowpeas. To determine cowpea genotypic variability to drought-tolerance, seventeen days-post sowing (DPS) greenhouse plants were subjected to 14-days drought stress without watering, then watered every 10-days at 25%, 50%, and 75% field capacity (FC) until maturity in two-trial experiments. Controls were well-watered at 100% FC every 3-days. Drought stress data were collected on plant height, stem diameter, chlorophyll content and terminal leaflet expansion rate. At maturity, 83 to 119 DPS, pod number, shoot and root biomass, and seed yield per plant were recorded. Data were combined and analyzed using analysis of variance. Drought tolerance was evaluated by percent change in performance and stress tolerance indexes. Drought stress in both trials impacted phenotypic expression. Plant height declined by 74%, stem diameter 18.2%, chlorophyll content, 47.6% terminal leaf length 83.2%, and width 85.2%. Pods per plant were reduced by 73% and seed yield by 98.8%. The estimated correlation between morpho-physiological and other yield-related traits of drought-tolerance indices verified that TVu 11987, LOBIA-I-SEFADE, and TVu 7362 were drought tolerant along with confirmed tolerant commercial cultivars California Blackeye No.5, Big Boy, and  Lady. These cultivars exhibited different stress-coping strategies of low water requirements and growth performance to yield reduction. Overall, the genotypic performance recorded as drought-tolerant characteristics may be recommended as potential screening factors for donor cultivar traits in cowpea breeding programs.

Water Deficit Stress Tolerance Potential of Newly Developed Wheat Genotypes for Better Yield Based on Agronomic Traits and Stress Tolerance Indices: Physio-Biochemical Responses, Lipid Peroxidation and Antioxidative Defense Mechanism.

Changing environmental conditions, fresh water shortages for irrigation and the rapid increase in world population have created the problems of food insecurity and malnutrition. Different strategies, including the development of water stress-tolerant, high-yielding genotypes through breeding are used to fulfil the world food demand. The present study was conducted for the selection of high-yielding, drought-tolerant wheat genotypes, considering different morpho-physio-biochemical, agronomic and yield attributes in relation to the stress tolerance indices (STI). The experiment was carried out in field in a split-plot arrangement. Water deficit stress was maintained based on the number of irrigations. All genotypes showed a differential decreasing trend in different agronomic traits. However, the increasing or decreasing trend in leaf photosynthetic pigments, non-enzymatic and enzymatic antioxidants under limited water supply also found to be genotype-specific. Genotypes MP1, MP3, MP5, MP8 and MP10 performed better regarding the yield performance under water deficit stress, which was associated with their better maintenance of water relations, photosynthetic pigments and antioxidative defense mechanisms. In conclusion, the physio-biochemical mechanisms should also be considered as the part of breeding programs for the selection of stress-tolerant genotypes, along with agronomic traits, in wheat.

MdGH3.6 is targeted by MdMYB94 and plays a negative role in apple water-deficit stress tolerance.

Drought significantly limits apple fruit production and quality. Decoding the key genes involved in drought stress tolerance is important for breeding varieties with improved drought resistance. Here, we identified GRETCHEN HAGEN3.6 (GH3.6), an indole-3-acetic acid (IAA) conjugating enzyme, to be a negative regulator of water-deficit stress tolerance in apple. Overexpressing MdGH3.6 reduced IAA content, adventitious root number, root length and water-deficit stress tolerance, whereas knocking down MdGH3.6 and its close paralogs increased IAA content, adventitious root number, root length and water-deficit stress tolerance. Moreover, MdGH3.6 negatively regulated the expression of wax biosynthetic genes under water-deficit stress and thus negatively regulated cuticular wax content. Additionally, MdGH3.6 negatively regulated reactive oxygen species scavengers, including antioxidant enzymes and metabolites involved in the phenylpropanoid and flavonoid pathway in response to water-deficit stress. Further study revealed that the homolog of transcription factor AtMYB94, rather than AtMYB96, could bind to the MdGH3.6 promoter and negatively regulated its expression under water-deficit stress conditions in apple. Overall, our results identify a candidate gene for the improvement of drought resistance in fruit trees.

Foliar silicate fertilization assessment on bean development and its water deficit stress tolerance

Bean’s productivity is below its productive potential, and among the related factors is the sensitivity to water deficiency. Silicate fertilization may aid to better tolerate this abiotic stress. Therefore, this work aims to evaluate the effects of foliar silicon (Si) doses in the development and tolerance of water deficiency for the bean’s cultivation. The experiment was conducted in a greenhouse, with a completely randomized block design in a 6x2 factorial scheme with four repetitions. Six doses of silicon (0; 0.5; 1.0; 1.5; 2.0; 2.5 kg Si ha-1) with and without water deficiency in flowering were used. The pots with a capacity of 2 L were filled with dystrophic Red Argisol, and they were maintained with automatic irrigation. The leaf temperature (TF) was analyzed daily, and at the end of the cycle, the plants’ height, aerial and root fresh and dry matter, the number of grains per plant, the number of grains per pod, the number of pods per plant, pod length, and grain fresh and dry matter were determined. After water deficit stress, the percentage of absolute integrity and relative water capacity were determined. The water condition reflected differences in plant height, grain dry matter, number of grains per plant, pods per plant, and the foliar temperature. The silicon doses did not influence the development and tolerance to water deficit for the bean culture.

OsJAZ9 is involved in water-deficit stress tolerance by regulating leaf width and stomatal density in rice

Drought stress poses a severe threat to grain yield in rice. Our previous report demonstrated the role of OsJAZ9 in potassium homeostasis by modulating Jasmonic Acid (JA) signalling. While both potassium (K) and JA are known to have an important role in drought stress response, JA's repressor, i.e., JAZs' role in drought stress, remains elusive. Here we report that OsJAZ9 plays a critical role in rice water-deficit stress tolerance via influencing JA and ABA signalling. Overexpression of OsJAZ9 led to the enhanced ABA and JA levels. Our data further revealed that exogenous JA application antagonises the ABA-mediated inhibition of seed germination. Further, OsJAZ9 overexpression reduces leaf width and stomata density, leading to lower leaf transpiration rates than WT. This reduced transpiration and higher K content as osmoticum improved the water-deficit stress tolerance in OsJAZ9 overexpression lines. On the contrary, OsJAZ9 RNAi lines displayed enhanced sensitivity towards water-deficit stress. Our data provide new insights on the role of JA signalling repressors in rice response to water-deficit stress.

Metabolic profiling of epidermal and mesophyll tissues under water-deficit stress in Opuntia ficus-indica reveals stress-adaptive metabolic responses.

Cactus pear (Opuntia ficus-indica) is a high productivity species within the Cactaceae grown in many semiarid parts of the world for food, fodder, forage, and biofuels. O. ficus-indica utilises obligate crassulacean acid metabolism (CAM), an adaptation that greatly improves water-use efficiency (WUE) and reduces crop water usage. To better understand CAM-related metabolites and water-deficit stress responses of O. ficus-indica, comparative metabolic profiling was performed on mesophyll and epidermal tissues collected from well-watered and water-deficit stressed cladodes at 50% relative water content (RWC). Tissues were collected over a 24-h period to identify metabolite levels throughout the diel cycle and analysed using a combination of acidic/basic ultra-high-performance liquid chromatography/tandem mass spectrometry (UHPLC/MS/MS) and gas chromatography/mass spectrometry (GC/MS) platforms. A total of 382 metabolites, including 210 (55%) named and 172 (45%) unnamed compounds, were characterised across both tissues. Most tricarboxylic acid (TCA) cycle and glycolysis intermediates were depleted in plants undergoing water-deficit stress indicative of CAM idling or post-idling, while the raffinose family oligosaccharides (RFO) accumulated in both mesophyll and epidermal tissues as osmoprotectants. Levels of reduced glutathione and other metabolites of the ascorbate cycle as well as oxylipins, stress hormones such as traumatic acid, and nucleotide degradation products were increased under water-deficit stress conditions. Notably, tryptophan accumulation, an atypical response, was significantly (24-fold) higher during all time points in water-deficit stressed mesophyll tissue compared with well-watered controls. Many of the metabolite increases were indicative of a highly oxidising environment under water-deficit stress. A total of 34 unnamed metabolites also accumulated in response to water-deficit stress indicating that such compounds might play important roles in water-deficit stress tolerance.

Identification of the SHINE clade of AP2/ERF domain transcription factors genes in Carica papaya; Their gene expression and their possible role in wax accumulation and water deficit stress tolerance in a wild and a commercial papaya genotypes

Climate change has resulted in alterations in temperature, soil salinity and droughts in many parts of the world. Carica papaya is one of the most important tropical fruits worldwide, although it is considered as a tolerant crop, water deficit stress affects its production. The aim of the present work was first to identify genes of the SHINE clade of AP2/ERF domain in the genome of C. papaya also, to characterize and compare the physiological performance, the total content of waxes and the expression levels of genes involved in wax biosynthesis in two papaya genotypes of contrasting tolerance (Maradol and Yuc1), when exposed to water deficit stress. Two genes (CpSHN1 and CpSHN2) were identified in C. papaya. It was clear that under water deficit stress, Yuc1 (a wild genotype collected at its center of origin), accumulated more cuticular waxes and had higher expression of both CpSHN1 and CpSHN2 genes than Maradol. This increased wax content might partly contribute to the higher water-deficit stress tolerance observed in Yuc1. Our results suggest that in response to water-deficit stress, CpSHN genes are involved in wax biosynthesis in C. papaya, allowing the accumulation of waxes (particularly alkanes). Both genotypes, showed tolerance to water stress, however the ability of Yuc1 to upregulate stress tolerance related genes faster than Maradol, might have favored an increased amount of waxes in leaves, contributing partly to its greater water-deficit stress tolerance than its commercial counterpart Maradol. The expression levels of CpSHN1 increased 30-fold in Yuc1 in response to water deficits and this was correlated with its superior ability to accumulate waxes. Although more studies are needed to further evaluate the functionality of CpSHN in water-limiting environments, our results suggest that CpSHN1 might be a good candidate gene to increase the water-deficit stress tolerance of this important tropical species.

RESPONSE OF SOME EXOTIC BREAD WHEAT GENOTYPES TO REDUCED IRRIGATION IN NORTH DELTA REGION OF EGYPT

Water deficit is one of the most constraints to wheat production in Egypt and worldwide. Therefore, sixteen exotic lines and two local cultivars of bread wheat were evaluated under normal (five irrigation) and water deficit stress (the planting irrigation only) conditions during 2017/18 and 2018/19 growing seasons at Sakha Agricultural Research Station. The current study aimed to enhance the breeding program with lines tolerant to water deficit stress. The two seasons and two water treatments showed sufficient genetic variability among the studied genotypes. Most studied traits showed higher values in the second season compared to the first one. All mean values of the studied traits decreased under water deficit stress. High values of grain and biological yields, number of spikes m-2 , grain filling period and rate were the most contributors to water deficit stress tolerance. line 1, line 16, line 15 and line 11 had high yielding ability and relative tolerance under water deficit stress. Misr 1 and Giza 171 cultivars were proved to be suitable cultivars under reduced irrigation. The exotics line 3, line 5 and line 9 could be used to enhance wheat breeding program for water deficit stress tolerance.

The Arabidopsis transcription factor LBD15 mediates ABA signaling and tolerance of water-deficit stress by regulating ABI4 expression.

To survive, sessile plants must adapt to grow and develop when facing water-deficit stress. However, the molecular mechanisms underlying fine-tuning of the antagonistic action between stress response and growth remain to be determined. Here, plants overexpressing Lateral Organ Boundaries Domain 15 (LBD15) showed abscisic acid (ABA) hypersensitivity and tolerance of water-deficit stress, whereas the loss-of-function mutant lbd15 presented decreased sensitivity to ABA and increased sensitivity to water-deficit stress. Further analysis revealed that LBD15 directly binds to the promoter of the ABA signaling pathway gene ABSCISIC ACID INSENSITIVE4 (ABI4) to activate its expression, thereby forming an LBD15-ABI4 cascade to optimally regulate ABA signaling-mediated plant growth and tolerance of water-deficit stress. In addition, drought stress-induced ABA signaling promoted LBD15 expression, which directly activates expression of ABI4 to close stomata. As a result, water loss is reduced, and then water-deficit stress tolerance is increased. The results of this study reveal a molecular mechanism by which LBD15 coordinates and balances plant growth and resistance to water-deficit stress.

Ectopic expression of DJ-1/PfpI domain containing Erianthus arundinaceus Glyoxalase III (EaGly III) enhances drought tolerance in sugarcane.

Sugarcane transgenic overexpressing EaGly III from Erianthus arundinaceus showed enhanced water deficit stress tolerance. Methylglyoxal (MG), an α-ketoaldehyde formed from either glycolysis or TCA cycle, is capable of causing total cellular damage via the generation of reactive oxygen species (ROS), advanced glycation end products (AGEs) and nucleic acid degradation. Glyoxalase pathway is a ubiquitous pathway known for detoxification of MG, involving key enzymes glyoxalase I (Gly I) and glyoxalase II (Gly II). Recently, a novel and an additional enzyme in glyoxalase pathway, viz., glyoxalase III (Gly III), has been discovered which possesses DJ-1/PfpI domain recognized for detoxifying MG in a single step process without requirement of any coenzyme. In the present study, a Gly III gene isolated from Erianthus arundinaceus, a wild relative of sugarcane, overexpressed in commercially cultivated sugarcane hybrid Co 86032 was assessed for drought tolerance. Morphometric observations revealed that transgenic sugarcane overexpressing EaGly III acquired drought tolerance trait. Oxidative damage caused by triggering generation of ROS has been determined to be low in transgenic plants as compared to wild type (WT). Transgenics resulted in higher relative water content, chlorophyll content, gas exchange parameters, photosynthetic efficiency, proline content and soluble sugars upon water deficit stress. In addition, higher and stable level of superoxide dismutase and peroxidase activities were observed along with minimal lipid peroxidation during drought stress signifying the tolerance mechanism exhibited by transgenic events. There was no significant structural change observed in the root anatomy of transgenic plants. Altogether, EaGly III gene could be considered as a potential candidate for conferring water deficit stress tolerance for sugarcane and other agricultural crops.

Diallel Cross in Potato Cultivars (Solanum tuberosum L.) and Evaluation of Their Progenies Under Deficit Water Stress

This study was performed to assess superior potato clones for agronomic traits and water deficit stress tolerance in laboratory and greenhouse settings over 3 years (2016–2018). Four cultivars, ‘Satina,’ ‘Caesar,’ Savalan,’ and ‘Agria’ were used as parents and crossed by mutual hybridization based on a diallel cross using the Griffing III method. Of 279 successful crosses, 7,980 true potato seeds from 12 breeding populations were obtained, from which 2,313 seeds germinated and 244 hybrids were selected. The selected hybrids were cultured in triplicate in a splitplot based on a randomized complete block design. The main factor consisted of three levels of irrigation (100%, 80%, and 60% of available water) and a subfactor of 12 populations (♀‘Agria’ × ‘Satina’♂, ♀‘Agria’ × ‘Caesar’♂, ♀‘Agria’ × ‘Savalan’♂, ♀‘Satina’ × ‘Agria’♂, ♀‘Satina’ × ‘Caesar’♂, ♀‘Satina’ × ‘Savalan’♂, ♀‘Caesar’ × ‘Satina’♂, ♀‘Caesar’ × ‘Agria’♂, ♀‘Caesar’ × ‘Savalan’♂, ♀‘Savalan’ × ‘Satina’♂, ♀‘Savalan’ × ‘Agria’♂, and ♀‘Savalan’ × ‘Caesar’♂). In all three environmental conditions, the highest tuber yield and tuber weight per plant were related to ♀‘Agria’ × ‘Caesar’♂. The most general combining ability that produced positive and significant tuber yield in mild and severe stress conditions was in ‘Agria’ and ‘Caesar’ cultivars. Therefore, these cultivars can easily transfer these traits to offspring and increase the expression of these traits. The specific combining ability between potato cultivars had positive and significant effects on tuber yield under the growth conditions tested. These crosses can be used for the production of drought resistant potato clones.

Morpho-Physiological Traits of Soybean as Affected by Drought

An experiment was conducted to study the effects of water deficit stress on morphophysiological parameters in soybean plant in pots at the Department of Agronomy, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh during February to June, 2018. Seven soybean genotypes namely,i) G00081 ii) G00056 iii) Shohag iv) G00078 v) G00137 vi) G00035 and vii) G00060 were grown in two watering regimes viz. control (80% of the field capacity) and water deficit stress (50% of the field capacity). Morpho-physiological traits including plant height, number of leaf, relative water content, water saturation deficit, chlorophyll, proline, dry matter and yield were investigated. Results indicated that genotypic variability was found in water deficit stress tolerance in soybean. It was found that leaf of the genotype G00081 maintained higher water content, higher accumulation of prolineas well as less reduction of chlorophyll compared to other genotypes studied. Total dry matter accumulation and grain yield plant-1was also higher in this genotype. Genotype G00081 also showed relatively higher water deficit stress tolerance. On the contrary, G00035 was found to be susceptible showing lower yield. Higher water deficit stress tolerance in G00081 was attributed to higher relative leaf water and chlorophylls with accumulation of higher amount of proline.
 Bangladesh Agron. J. 2019, 22(2): 41-54